Method of recording and transferring design indicia

ABSTRACT

A HEAT-SENSITIVIE RECORDING LAYER OF THE TYPE DISCLOSED IN USP 3,476,937 AND FORMED ESSENTIALLY OF A DISPERSION OF SOLID HYDROPHOBIC THERMOPLASTIC POLYMER PARTICLES IN A HYDROPHILIC BINDER, AFTER EXPOSURE TO A HEAT PATTERN TO REDUCE THE WATER PERMEABILITY IN THE HEATED AREAS OF THE LAYER AND AFTER WASHING TO REMOVE FROM THE THE LAYER THE AREAS THEREOF OF UNCHANGED WATER-SOLUBILITY, LEAVING THE HEATED AREA THEREOF IN RELIEF, IS CONTACTED WITH A RECEIVING MATERIAL AND SUBSTANTIAL MECHANICAL PRESSURE IS APPLIED TO SUCH REMAINING PORTIONS TO CAUSE THEM TO ADHERE TO THE RECEIVING MATERIAL SO THAT WHEN THE RECORDING LAYER AND THE RECEIVING MATERIAL ARE SEPARATED BY PEELING, A STRATUM OF THE REMAINING PORTIONS OF THE RECORDING LAYER REMAINS ADHERED TO THE RECEIVING MATERIAL FORMING THEREON A REPRODUCTION OF THE ORIGINAL HEAT PATTERN APPLIED TO THE HEAT-SENSITIVE RECORDING LAYER. EITHER OR BOTH OF THE SURFACE OF THE RECORDING LAYER AND RECEIVING MATERIAL CAN BE PROVIDED WITH A WEAKLY ADHESIVE LAYER TO FACILITATE TRANSFER OF THE STRATUM OF THE RECORDING LAYER TO THE RECEIVING MATERIAL.

United States Patent 3,674,588 METHOD OF RECORDING AND TRANSFERRINGDESIGN INDICIA Jan Bernard Lambrechts, Antwerp, Belgium, assignor toAgfa-Gevaert, Mortsel, Belgium No Drawing. Filed Oct. 2, 1968, Ser. No.764,631 Claims priority, application Great Britain, Oct. 2, 1967,44,794/ 67 Int. Cl. B4lm 5/26 US. Cl. 156-230 9 Claims ABSTRACT OF THEDISCLOSURE A heat-sensitive recording layer of the type disclosed in USP3,476,937 and formed essentially of a dispersion of solid hydrophobicthermoplastic polymer particles in a hydrophilic binder, after exposureto a heat pattern to reduce the water permeability in the heated areasof the layer and after washing to remove from the layer the areasthereof of unchanged water-solubility, leaving the heated area thereofin relief, is contacted with a receiving material and substantialmechanical pressure is applied to such remaining portions to cause themto adhere to the receiving material so that when the recording layer andthe receiving material are separated by peeling, a stratum of theremaining portions of the recording layer remains adhered to thereceiving material forming thereon a reproduction of the original heatpattern applied to the heat-sensitive recording layer. Either or both ofthe surfaces of the recording layer and receiving material can beprovided with a weakly adhesive layer to facilitate transfer of thestratum of the recording layer to the receiving material.

This invention relates to information-recording materials and methods.

It has been proposed to record information by information-wise heatingand/or subjecting to pressure a water-permeable recording layer whichunder the action of such heat and/or pressure becomes water-impermeableor less water-permeable. In consequence of the information-wise heatingand/ or pressurising of the layer the information is therefore recordedin terms of a difference in the water-permeabilities of different areasof said recording layer.

The parts of the recording layer in the still waterpermeable or mostwater-permeable areas can then be removed, leaving a record in relief.

The present invention is concerned with improvements and developments ofrecording methods of this type.

According to the present invention information is recorded by a methodas above referred to and at least a stratum of the recording layer inthose areas where it has been rendered water-impermeable or lesswaterpermeable by the information-wise heating and/or pressurising, istransferred by pressure to a receiving surface. The transfer pressuremay be exerted by a stylus.

In order that this transfer can occur, the material to be transferredmust adhere to the receiving surface sufficiently well to separate fromthe recording material when this material and the receiving surface areseparated following the application of the transfer pressure. In orderto promote this adhesion, either the recording material or the receivingsurface or both, may bear a layer of ad- Patented July 4, 1972 hesivematerial, e.g. a waxy adhesive. Suitable waxy adhesives are thosereferred to in United Kingdom patent specification 906,934 which alsorelates to the transfer of recorded information but is concerned withthe transfer of letters or other indicia which have been printed onto acarrier sheet with a film-forming ink. Further examples of adhesives aregiven later in this specification.

The present invention also includes informationrecording sets comprising(a) a recording material with a water-permeable recording layer whichcan be rendered water-impermeable or less water-permeable in anyselected areas thereof by heating and/or subjecting the layer topressure in such area, and (b) a receiving material to which, aftersubjection of a given area or areas of such recording layer to heat and/or pressure as aforesaid, at least a stratum of such recording layer, inthat area or areas, will transfer if the materials are placed in contactand subjected to suitable pressure in the areas where the transfer is totake place.

Another factor of importance for the performance of the invention is ofcourse the degree of adhesion between the information-wise heated and/orpressurized portions of the recording layer and the sheet, film or thelike constituting the support for such layer. The adhesion should makepossible a quick release of the recording layer under pressure againstthe receiving surface, but must be sufiiciently strong to preventpremature separation of the said heated and/or pressurized portions,e.g. during the step of removing the still water-permeable or the morewater-permeable parts of the recording layer, if such removal isnecessary. A sufiicient but not too strong adherence of the recordinglayer to its support can be realised by the use of an adhesive orsubbing layer which holds the recording layer more strongly after suchadhesive or subbing layer has been heated to a certain extent. Byinformation-wise heating the recording material the change in therecording layer whereby it becomes water-impermeable or lesswater-permeable in the heated or most strongly heated areas isaccompanied by a strengthening of the anchorage of the recording layerin those areas but not in the other areas. Instead of forming anadhesive or subbing layer in this way, the recording layer may be borneby a self-supporting layer or sheet which reacts to heat in the waydescribed.

An important preferred feature of the invention is the use of arecording layer comprising a network of hydrophobic thermoplasticpolymer particles, solid at room temperature, or comprising hydrophobicthermoplastic polymer particles dispersed in a continuous phasehydrophilic binder medium. Preferred recording materials with thesefeatures are described in Belgian patent specification 656,713, in thepublished Dutch Pat. application 6,606,719, and in copending applicationSN 421,861, filed Dec. 29, 1964, now USP 3,476,937, issued Nov. 4, 1969.The specifications of the said Belgian patent specification and of thesaid Dutch patent application should be read in conjunction herewith andare deemed to form part of the present disclosure.

When using a recording layer comprising hydrophobic thermoplasticpolymer particles, a good but not too strong adhesion of the recordinglayer to the support in the areas which are information-wise heatedand/or subjected to pressure can be achieved by applying the recordinglayer to an interlayer or self-supporting sheet composed of orcomprising substance(s) having a melting or softening point lower than,equal to or not substantially higher than that of the hydrophobicthermoplastic particles contained in the hydrophilic binder of therecording layer. Preferably said interlayer or self-supporting sheetcomprises a hydrophobic thermoplastic polymer or polymers having asoftening or melting point lower than that of the hydrophobicthermoplastic polymer particles in the recording layer so that suchthermoplastic substance(s) in the underlying layer can be softened bythe heat to which that layer is exposed during information-wise heatingof the recording layer. A certain content of wetting agent and/orhydrophilic binder may be incorporated in the interlayer or applied tothe self-supporting sheet to provide a good anchorage. The interlayerpreferably comprises a dispersion of thermoplastic polymer particles(latex) in a continuous phase, e.g. a hydrophilic binder, preferably ahydrophilic binder which is less soluble in water than the hydrophilicbinder (if any) in the recording layer. Further information concerningsuitable adhesive interlayers or self-supporting sheets for bearing therecording layer is given in the specifications filed in Belgian patentspecification 692,422.

It is preferred to use a recording layer at least the greater part byvolume of which is formed by a dispersion of particles wholly or mainlyconsisting of a hydrophobic thermoplastic polymeric material, solid atroom temperature, in a hydrophilic hinder, the weight ratio of thepolymer particles to the binder being in excess of 1:11. It is alsopreferred for the recording layer to be normally water-soluble, i.e. arecording layer from which the nonheated or only slightly heatedportions can be removed by a washing treatment after the layer has beeninformation-wise heated.

In general, it is intended that the recording layer will contain pigmentor dye so that a clearly readable record of the information exists whenthe still water-permeable portions of the recording layer have beenremoved following the information-wise heating and/or pressurizing. Bythe transfer of the remaining portions of the recording layer, or astratum thereof, a likewise visible record is formed on the receivingsurface.

Instead of removing the still Water-permeable portions of the recordinglayer containing a dye or pigment, a readable record can be formedfollowing the information-wise heating and/or pressurizing, by treatmentwith a bleaching solution or other substance which destroys ortransforms the colour in the still water-permeable areas of therecording layer, i.e. in the areas into which the agent can penetrateduring the treatment. It is also possible to form a pigment in situ inthe recording material. Thus, a recording material can be used which, asdescribed in the Dutch and Belgian patent specifications hereinbeforereferred to and in the aforesaid corresponding United Kingdomspecifications, comprises a light-sensitive ingredient such as a silverhalide emulsion, from which a visible image-forming substance can beformed by exposure of the recording material to light. If such arecording material is record-wise irradiated with light, a visible imageforms in the irradiated areas and if the recording layer issimultaneously or subsequently heated in those areas to render themwater-impermeable or less water-permeable, the transfer of the imageportions to the receiving surface can be achieved without previouslyremoving substance from the recording layer in the other areas. Theseprocedures constitute modification of the recording method hereinbeforedefined and the invention includes this modification.

If the recording layer can be rendered selectively waterimpermeable byrecord-wise subjecting it to pressure, the pressure can be exerted bymechanical means such as typewriter keys. The present invention ishowever mainly concerned with recording involving record-wise heating ofthe recording layer. Record-wise heating can be achieved by heatconduction from an original during contact of the recording materialwith the original while this is exposed to infrared radiation, providedthe original has infraredabsorbing indicia. Certain preferredembodiments of the invention however use a recording material in whichthe recording layer or a layer in heat-conductive relationship therewithcontains distributed radiation-absorbing substance so that the recordinglayer can be record-wise heated by record-wise exposing the recordingmaterial to radiation of sufiicient intensity. The irradiation can bewith infrared or other radiation which can be absorbed by thedistributed substance and converted thereby to heat. Special importanceattaches to the use of light-absorbing substances and record-wiseexposure of the recording material to high-intensty light radiation(e.g. flash exposure). If the radiation absorbing substance isdistributed over the Whole area of the recording material the exposureto radiation must be a record-wise exposure but if theradiation-absorbing substance is distributed record-wise in therecording material, as in the case where this substance is formed insitu from a record-wise exposed light-sensitive ingredient, then therequired record in terms of a difference in the water-permeabilities ofdifferent areas of the recording layer can be created by an overallnon-differential irradiation of the recording material. In connectionwith these embodiments of the invention reference is made to theaforesaid Belgian and Dutch specifications and the corresponding UnitedKingdom patent specifications, and also to the Beligan patentspecification 681,138, which discloses recording materials containingdistributed susbtances which absorb light in a part only of the visiblelight spectrum.

According to an embodiment desribed in said published Dutch patentspecification for recording and producing a copy of an original, animage-Wise differential in watersolubility of the recording layer isutilised for removing the recording layer in the non-heated orinsufficiently heated areas e.g. by washing away or degrading thehydrophilic binder. A copy of the original built up by coloured imageportions left after the Washing of the nonexposed portions is obtained.

So, a preferred method of recording and transferring indicia orhalf-tone designs according to the present invention contains the stepsof:

(a) providing a thermosensitive recording material that contains aheat-sensitive water-permeable layer, which by the action of heatbecomes less permeable to water and less soluble in water and comprisesfor the greater part by volume a dispersion containing thermoplasticparticles dispersed in a hydrophilic binder preferably in a weight ratiogreater than 1:1.

(b) heating the heat-sensitive layer in conformity with the indicia ordesign to be transferred whereby the heated portions become less solublein water.

(c) washing away only the non-heated portions of the recording layer.

(d) bringing the heated portions of the recording layer in contact witha receptor material and applying substantial pressure by means of e.g. astylus to the portions corresponding with the indicia selected to betransferred so that by peeling apart the recording layer and receptorsheet, a stratum of the recording layer corresponding with the pressedportions is left on the receptor sheet.

The support of the heat-sensitive recording material has to makepossible a quick release of the recording layer by pressure and topossess a sufficient adherence to the recording layer to prevent totalremoval of the recording layer in the washing away step. As alreadymentioned, suitable adhesive or subbing layers for obtaining asufiicient but not too strong adherence to the support are described inthe Belgian patent specification 692,422. Preferred supports are of theresin type e.g. polyethylene terephthalate.

Particulars about the type of thermoplastic particles and thehydrophilic binder wherein they are dispersed can be found in theBelgian patent specifications 656,713 and 681,138. Preferably theheat-sensitive layer used in the present invention incorporatesparticles of hydrophobic thermoplastic polymeric material which is solidat room temperature (20 C.) and which have been applied as a latex. Thehydrophilic binder is preferably soluble in water at room temperature,so that in view of this aim poly-N-vinyl-pyrrolidone is preferred.

As colouring material in the recording material, pigments or solubledyes can be used, preferably in an amount sufiicient to reach an opticaldensity of at least 1. Preferably carbon black is incorporated into therecording layer when black prints have to be obtained. In order toobtain coloured prints, dyes or pigments absorbing the desiredwavelength part of the visible spectrum are applied in the recordinglayer. For obtaining smudge-free transfer prints diffusion-fast pigmentse.g. Pigmosol dyes (Pigmosol is a registered trademark of BadischeAnilin- & Soda- Fabrik A.G. Ludwigshafen (Rhine), Germany, for organicpigment dyes which are mixed with a dispersing agent for aqueousmedium), are used.

Either the recording material containing already the indicia or thereceptor sheet may be provided with a Waxy adhesive so that the transferwill occur more easily. Waxy adhesives suited for that purpose aredescribed in the United Kingdom patent specification 906,934 and arementioned in the examples of the present description of the invention.Other adhesives having pressure-sensitive properties are well known tothose skilled in the art. In this respect reference is made particularlyto the adhesives known as paracons described in the United States PatentSpecification 2,443,613.

Heat recording wherein recording materials according to the presentinvention are used can proceed in difierent ways according to the methodby which heat is supplied to the recording element.

According to a common heat-recording process the heat accumulated in theimage areas of an original by infrared irradiation may be used toproduce the necessary image differentiation in the heat-recording layer.

In another heat-recording technique the light-absorbing andheat-generating properties of substances dispersed or dissolved in thehydrophilic binder of the recording layer are used. By irradiating therecording layer containing substauce(s) that absorb(s) copying light(infrared radiation and visible light, or visible light alone) andconvert(s) that light radiation into heat, an internal image-wiseheating effects the desired differentiation in water-absorption powerand water-solubility of the recording layer.

According to a particular embodiment, an image of heat-absorbingmaterial is produced in the interlayer or recording layer by means oflight-sensitive silver halide contained in both or one of said layers.The said silver halide is image-wise exposed and developed. The silverimage obtained acts as a heat-absorbing image for producing by anoverall exposure to light, e.g. infrared radiation, the desired usefuldiflerentiation of water-solubility.

In the above embodiments transmission exposure or contact-exposure aswell as reflex exposure can be applied. When applying a reflex exposure,the intensity of exposure, the concentration of coloured substancesabsorbing copying light, and the thermoplastic polymer particles presentin the recording layer are chosen in such a way, that the heatingresulting from the absorption of the light rays directed to the originaland striking undifferentially the heat-sensitive layer causespractically no or only a slight loss of water-permeability and/orwater-solubility in the heat-sensitive recording layer. In other Words,the imagewise heat resulting from the image-wise reflected light mustproduce in the recording layer the practically useful differentiation inwater-solubility. Reflex copying, however is not very interesting here,since due to the need of a partial transmittance of the recording layerno very dense transfer prints can be obtained.

When applying a transmission or contact printing proc- 6 ess however,the recording layer can have an optical density of at least 1 resultingfrom the coloured substance (5) to be transferred in the stratum of therecording layer.

According to a special embodiment light-absorbing substances thatconvert absorbed light into heat and which can be bleached or leachedout over the whole area of the recording material, i.e. alike in theinformation-wise heated and in the non-heated areas, e.g. during thewash ing away of the water-soluble or most water-soluble portions of therecording layer, are used. If, together with said substance, pigments ordyes are incorporated which are not removed or bleached by the liquidtreatment, dye images in any colour (e.g. also yellow) without dark orgrey background (resulting from the light absorbing heatgenerating dyes)can be produced (see our co-pending US. patent application No. 764,622filed on even date herewith).

Multicolour images can be produced by transfer in register of colouredpart images corresponding with the subtractive colours (cyan, magenta,yellow) of a multicoloured original.

Such a multicolour reproduction offers an interesting application in thefield of printing correction known as color proofing.

Color proofing materials serve to form a proof for submission to theprinter or client to give an idea of a multicolour reproduction as willbe produced by imagewise over-printing of three coloured inks (yellow,magenta, cyan) and black, printed at the strength normally used inpractice. The proof obtained with a color proofing material allows todetermine the necessary corrections of the internegatives used inpreparing the etching resists and to adapt the exposure conditions.

In a method for preparing such a colour proof use can be made of amulticolour silver halide photographic material which is exposed throughthe screened black-andwhite internegative transparencies whichrespectively correspond with the cyan, magenta, and yellow part imagesof a multicolour original. The difliculty associated with said methodresides in finding the right colour couplers for forming dyes having anabsorption spectrum practically identical to that of the printing dyesor pigments used. The method of the present invention offers a solutionto that problem in that properly selected dyestuffs or pigments with theright absorption spectrum can be incorporated in non-mlgratory stateinto the heat-sensitive recording layer. The production of amulti-colour proof according to the present invention is realized bysuccessively transferring in register heated non-washed away colouredportions (black, cyan, magenta, yellow) of four hydrophilicthermographic layers suited for water-solubility differentiation byheating and containing respectively a black, a cyan, a magenta andyellow pigment or pigment composition. The black toner can be a black orgrey pigment e.g. carbon or dark-coloured metal particles, the sulphidesand oxides thereof e.g. nickel, lead, silver, bismuth, lead dioxide,copper (II) oxide, and copper (II) sulphide. The black-toned materialpreferably contains carbon black in the heat-sensitive layer, whichpreferably is applied to a subbing or interlayer of the type describedin the Belgian patent specification 692,422. The cyan, magenta andyellow coloured thermographic layers contain together with dark heatgenerating water-soluble dyes (see the United States patent application764,622) a dye or pigment, which is resistant to diffusion and which hasan absorption spectrum as close as possible to that of the colour of theprinting dye selected for each printing step (cyan, magenta, yellow).

As is known, the magenta ink pigments have unwanted absorptions in theblue spectral region, and to a much less extent in the red; the magentaink prints as if it were a true magenta ink plus yellow and a littlecyan. Normally suflicient correction is obtained by reducing the 7amount of yellow in proportion to the amount of magenta printed.

In color-proofing the correction must therefore be applied to thedensity or concentration of the yellow dye in the thermosensitive layercontaining that dye.

The cyan ink pigments have unwanted absorptions in the blue and greenspectral regions; the cyan ink prints as if it were a true cyan ink plusmagenta and yellow. Correction can be made by reducing the amount ofmagenta in the magenta layer in proportion to the amount of cyan and byreducing the amount of yellow in the yellow layer in proportion to theamount of cyan in the cyan layer.

The yellow ink pigments normally approaches the ideal and no correctionis necessary unless it is a specially warm-ink (orange yellow) in whichcase it may be desirable to strengthen the magenta printed in the yellowareas.

The black printer tends to have excess density in colour areas. This canbe corrected by reducing the overall density of the black pigment andexposing the black toned thermosensitive layer in register through thethree separate black-and-white screened internegatives respectivelycorresponding with the cyan, magenta, and yellow part images of themulticolour original.

Diffusion-resistant pigments suitable for use in the color proofingsystem of the invention are the already mentioned Pigmosol dyes (tradename). These pigment dyes are very resistant to light, heat, acidity,and alkalinity. They are insoluble in hydrophilic colloids e.g. gelatinand poly-N-vinyl pyrrolidone, which colloids are preferably used inthermosensitive layers intended for use in the washing away technique.

In order to produce very sharp images one has to prevent lateraldiffusion of heat during the exposure. This can be realized by keepingthe exposure time very short, preferably not exceeding 10- sec.

Suitable radiation sources producing copying light of high intensity ina very small lapse of time and which are very suitable for applicationwith recording materials containing light-absorbing substancesconverting that light into heat are the so-called flash lamps. Goodresults are obtained with xenon gas discharge lamps, which can supply alight energy of 100 to 1000 watt. sec. in a time interval of 10 toseconds. These flash lamps emit a greater part of energy as visiblelight than as infrared light. Details on copying apparatus containingsuch a discharge lamp can be found in the Belgian patent specification664,868.

Self-evidently gas discharge lamps with a lower energy output can beused if the emitted energy is focused onto a relatively smallheat-sensitive area. So, e.g., a gas discharge lamp with an energyoutput of 40 watt. sec. is suited for copying 6 cm. x 6 cm. and 6 cm. x9 cm. originals on heat-sensitive materials as described in the presentinvention. For materials having an optical density of at least 1resulting from the presence in the recording layer of light-absorbingsubstances, a light energy of at least 0.1 watt. sec. per sq. cm. willbe required for the desired image differentiation. In practice anexposure of 0.3 watt. sec. per sq. cm. will provide satisfactoryresults. It is further self-explanatory that the exposure may be carriedout progressively or intermittently. In other words the original may bescanned, e.g. by a high-intensity light spot rapidly line-wise scanningthe original, or may be progressively exposed through a slit wherein,e.g. copying light of a tube-like radiation source is focused.

It is evident that the heat-sensitive recording material, before orduring the creation of the image-wise heat differentiation, can besubjected to overall heating to a cer' tain temperature below thetemperature at which a substantial decrease in permeability for water orsolubility in water takes place.

The following examples illustrate the present invention Without,however, limiting it thereto.

8 EXAMPLE 1 A poly(ethylene terephthalate) support of 0.1 mm. thicknessprovided a subbing layer is coated with the following composition prorata of 15 g. per sq. m.

G. 40% aqueous dispersion of polyethylene having a particle size of 0.11, an average molecular weight of 2000, and a melting point between andC. 37.5 20% aqueous dispersion of the copolymer obtained from themixture of 88% by weight of vinylidene chloride, 10% of N-butylmaleimideand 2% of itaconic acid 37.5 30% aqueous dispersion of silica with aparticle size of 0.025;. 37.5 Ethanol 80 Water to make 1000 The coatedlayer was dried at 30 C. A thermo-sensitive layer comprising thefollowing ingredients was applied thereto pro rata of 20 g. per sq. m.:

The resulting layer was dried at 30 C. The material formed was thenbrought in contact with a negative comprising indicia letters, figures,etc. and exposed by means of a xenon vapour discharge lamp of 1000joule. The unexposed areas were washed away by means of a foam rubbersponge soaked with water. The positive indicia left were transferred toa receiving paper by rubbing the backside of the recording material bymeans of a pointed object.

EXAMPLE 2 A poly(ethylene terephthalate) support of 0.100 mm. thicknessprovided with a subbing layer was coated with the composition describedin Example 1 pro rata of 15 g. per sq. m.

The coated layer was dried at 30 C. A thermosensitive layer comprisingthe following ingredients was applied thereto pro rata of 20 g./sq.m.

G. 20% aqueous dispersion of polyethylene having an average molecularWeight of 7000 and a melting point of C. 172 20% aqueous solution ofpoly-N-vinyl pyrroliclone 67 16% carbon dispersion as described inExample 1 600 10% aqueous solution Antarox B 290 (trade name) 50 Waterto make 1000 The layer was dried at 30 C.

The resulting material was exposed and developed as described inExample 1. The positive black indicia left were transferred to areceiving paper by rubbing the backside of the recording material with apointed object.

EXAMPLE 3 A cellulose triacetate support of 0.1 mm. thickness was coatedwith a subbing layer having the composition described in Example 1. Athermo-sensitive layer comprising the following ingredients was appliedthereto pro rata of 20 g./sq. m.:

The coated layer was dried at 30 C.

The resulting material was exposed and developed as described in ExampleI. The positive indicia left after the washing step were transferred toa receiving paper by rubbing the backside of the recording material bymeans of a pointed object.

EXAMPLE 4 A poly(ethylene terephthalate) support having a thickness of0.1 mm. was coated with a subbing layer as described in Example 1. Athermo-sensitive layer comprising the following ingredients was appliedthereto pro rata of 20 g./sq. m.: l

G. 20% aqueous dispersion of polyethylene containing a non-ionogenicwetting agent, the polyethylene having an average molecular weight of7000 and a melting point of 130 C 150 30% aqueous dispersion ofpolyethylene having an average molecular weight of 7000 and a meltingpoint of 120 to 130 C. and containing an anionic wetting agent 15 16%carbon dispersion as described in Example 1 600 10% aqueous solution ofAntarox B 290 (trade name) The coated layer was dried at 30 C. Theresulting material was exposed and developed as described in Example l.The positive black indicia left after the washing step were transferredto a receiving paper by rubbing the backside with a pointed object.

EXAMPLE A poly(ethylene terephthalate) support of 0.1 mm. thickness wasprovided with a subbing layer as described in Example 1 pro rata of 20g. per sq. m. The coated layer was dried at 45 C. A thermo-sensitivelayer comprising the following ingredients was applied thereto pro rataof 13 g. per sq. m.:

The coated layer was dried at 30 C.

The resulting thermo-sensitive material was exposed reflectographicallywhile in contact with a positive line original in a common thermographicapparatus, e.g. a Thermofax apparatus type Secretary (trade name). Theareas corresponding with the image areas were heated and becomeinsoluble. The unheated portions were washed away with water, and thematerial was dried. A positive purple image legible through the back ofthe recording material was obtained. The purple image portions weretransferred to a receiving paper by rubbing the back of the recordingmaterial with a pointed object.

EXAMPLE 6 A poly(ethylene terephthalate) support having a thickness of0.1 mm. was coated with a subbing layer having the following compositionpro rata of 15 g./sq. m.:

G. 40% aqueous dispersion of polyethylene containing a non-ionogenicwetting agent and traces of an anionic wetting agent, the polyethylenehaving a particle size of 0.1a, an average molecular weight of 2000 anda melting point of 110 C. 37.5 20% aqueous dispersion ofpolyethylacrylate with a particle size of 0.05; and containing aswetting agent the sodium salt of oleylmethyltauride 37.5 30% aqueousdispersion of silicon dioxide with a particle size of 0025 37.5 Ethanol80 Water to 1000 The resulting layer was dried at 30 C.

The exposure and development steps were analogous to those described inExample 1. The positive black indicia left after the washing step weretransferred to a receiving paper by rubbing the backside of therecording material by means of a pointed object.

EXAMPLE 7 For improving the transfer of the recording layer indicia,formed as described in Examples 1, 2 and 3, the recording layer indiciawere coated with a subbing layer from a coating solution of 2.5% ofco(n-butyl acrylate/ vinyl acetate) (80/20) in acetone pro rata of 10 g.per sq. m.

EXAMPLE 8 For improving the transfer to the receiving paper of therecording layer indicia formed as described in the Examples 1, 2, 3 and4 the recording layer indicia were coated with a subbing layer from a2.5% solution in acetone of copoly(n-butyl acrylate/ vinyl acetate) 80/20) pro rata of 10 g./sq. m. The coated layer was dried at 20 to 30 C.

EXAMPLE 9 Example 8 was repeated, with the modification however, that a5% solution in acetone of poly(isobutyl methacrylate) was used forpreparing the subbing layer.

I claim:

1. A process of reproduction by the transfer of selected portions of adeveloped heat-sensitive recording layer, said process containing thesteps of:

(a) providing a thermosensitive recording material including aheat-sensitive water-permeable recording layer formed essentially of adispersion of solid hydrophobic thermoplastic polymer particles in ahydrophilic binder in a weight ratio of at least about 1: 1, said layerwhen subjected to heat becoming less permeable to water and less solublein water,

(b) applying a heat pattern corresponding to the portions to betransferred to said heat-sensitive layer, whereby the heated portionsbecome less soluble in water,

(c) washing away the portions of the heat-sensitive layer of unchangedwater-solubility,

(d) contacting the remaining portions of the recording layer with areceiving material and applying substantial mechanical pressure to suchportions so that by peeling apart the recording layer and receivingmaterial a stratum of the recording layer corresponding with the pressedportions adheres to the receiving material.

2. A process according to claim 1, wherein the nonheated portions of therecording layer are removed by abrasion when wet with water.

3. A process according to claim 1, wherein the recording layer containssubstances absorbing radiation in the range from visible light toinfrared and said heat pattern is created internally of the layer byimage-wise exposing the recording layer to such radiation which istransformed therein into heat.

4. A process according to claim 3, wherein the recording layer containsdispersed carbon particles in sufficient amount to impart to the layeran optical density of at least about 1.

5. A process according to claim 1, wherein the recording layer containswater-soluble dyes, which are removed from said layer by washing awaythe non-heated portions of the recording layer.

6. A process according to claim 1, wherein the said thermoplasticparticles are applied from a latex.

'7. A process according to claim L'Wherein the hydrophilic hinderpresent in the recording layer is soluble in water.

8. The process of claim 1 wherein said receiving material carries alayer of a weak adhesive which is brought into contact with theremaining portions of said recording layer.

9. The process of claim. 8 wherein said adhesive is a waxy material.

References Cited UNITED STATES PATENTS I 2,629,671 2/ 1953 Murray 1 17-83,121,162 2/1964 Roman et al; 250- 3,223,838 12/1965 Hoshino et a1.250-65 3,298,833 1/ 1967 Gaynor 250-65 X 3,405,265 10/1968 'Vrancken117-1.7X 3,464,353 9/1969 Bach et al 101-470 3,476,578 11/1969 Brinckman250-65 3,476,937 11/ 1969 Vrancken 250-65 3,479,953 11/1969 Ritzerfeld101-470 FOREIGN PATENTS 906,934 9/ 1962 Great Britain.

WILLIAM D. MARTIN, Primary Examiner M. SOFOCLEOUS, Assistant ExaminerUS. Cl. X.R.

ll736.l, 76 T, 93.31; 250-65.l; 101-470

